ECC errors and fan speed issue Mac Pro (late 2013)

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ECC errors and fan speed issue Mac Pro (late 2013)

Hi. I'm having a series of issues on a late 2013 Mac Pro. As I am in Thailand and to have the machine looked at it needs to be sent to Singapore, I'd like to try getting ideas here first.

I have been getting intermittent ECC errors (I have 4x32gb DIMM) that came with the machine (the machine belonged to my cousin new, it was rarely used, he gave it to me recently). ECC errors show on different DIMMS at different times. Sometimes when machine is running normal temperature (e.g. right now it is 56C), sometimes when machine is running hotter (e.g. running CPU intensive task, processor in mid 70's C). Sometimes no ECC errors.

And sometimes (like now, one or more of the slots shows as empty. The empty slot position(s) can change as well, there is no pattern to it.

I've tried various troubleshooting. I've used compressed air to remove any dust from the memory slots. I have deoxit gold but have not used it yet on the memory chip contacts.

I wondered if the fan might not be functioning properly. I have installed a hardware monitor (iSTAT Menus), and it shows the fan at 789-790 RPM. I ran a CPU intensive task for a few minutes in a piece of software I use regularly. CPU temperature rose to mid-70's C and at that point one DIMM showed ECC errors. The Fan never changed (rose to 792 RPM at one point, but no more). I've installed SMC Fan Control 2.6, and tried changing the minimum fan speed, but the fan speed doesn't change, it stays at approximately 790 RPM.

I have reset SMC controller. I have done a PRAM reset. Before PRAM reset, 128gb ram showing, one DIMM showing ECC errors. After PRAM reset, 96gb ram (one slot showing as empty), 1 DIMM showing errors.

Not sure where the errors are? Bad DIMM (but it would have to be all of them, as the errors move from chip to chip)? Bad slots (it would have to be all of them, as empty slot messages appear pretty randomly)? Bad fan (why won't the fan ever change RPM)? Bad everything?

Any assistance in troubleshooting before I have to send this out of the country would be helpful. I'm attaching a couple of screenshots taken just now.

Mac Pro, macOS High Sierra (10.13.3), Late 2013

Posted on Feb 11, 2018 11:55 PM

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Answer 1

macnmotion Author

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4 points

Feb 12, 2018 8:01 PM in response to Grant Bennet-Alder

This machine is the 2013 dark cylinder.

What's now a bit more confusing is that the DIMMs in the machine are labeled as 1333MHz. But as I showed you, the system is showing them as 1066MHz. Here is a screenshot of the DIMM label. Any idea why they would be running at 1066? Is the system running them more slowly because they aren't to spec?

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Answer 2

macnmotion Author

Level 1

4 points

Feb 12, 2018 6:58 PM in response to Grant Bennet-Alder

Hi Grant,

Thanks for taking the time to reply. As I mentioned I'm not the original owner, and didn't know that the memory in the machine didn't meet spec.

In any case, I do have an update. I went through a thorough trial and error process, moving each chip one at a time from slot to slot and starting up the machine. I've discovered that with two of the chips in slots 1 and 4, I've got 64gb of memory and after a day of hard use no errors showing. The other two chips, when inserted in slots 2 and 3, don't show up which I understand means errors are discovered on the chips during startup. Today I'm doing some very processor intensive tasks, my CPU is currently at 83C. The fan has finally kicked in, more than 1100 RPM. I guess yesterday I wasn't hot enough for the machine to kick in, and the memory errors are caused by 2 bad chips (or chips not meeting specs), not from overheating.

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Answer 3

Feb 12, 2018 7:10 PM in response to macnmotion

What specs are shown for those DIMMs in:

 menu > about this Mac > (system report) > Memory

If they are correct on that page, I would trust that page, and call the glossy memory summary page a false alarm.

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Answer 4

Feb 12, 2018 7:42 PM in response to macnmotion

1066 DIMMs were used in the mac pro silver tower 2009 model. The 2010 model with 6-core processors used 1333 DIMMs, and the Mac pro 2013 dark cylinder shipped with 1866 DIMMs. I believe that may all be the same shape DIMM.

32GB DIMMs are pricey, so the previous owner may have takes some liberties in installing cheaper, slower DIMMs. The Mac Pro line has a good record of being able to gearshift up and down to get a usable speed. Its error correction Hardware will fix single-bit errors, and halt on Multi-bit errors with a distinctive kernel panic.

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Answer 5

Feb 13, 2018 7:28 AM in response to macnmotion

I don't think users here have much experience with what that Mac Pro would do with RAMs that identify themselves as slower than standard. (the Mac can read the specified speed from each DIMM).

It would be very nice if they shifted down and worked slower instead of immediately error-ing out and being unusable. There may be code in there to start at the rated speed, and if that does not work error-free, to shift down one speed and try again.

I am also imagining the lab where the Mac Pro dark cylinder was being developed. It may be that the developers added some code to allow the use of slower DIMMs during the prototype phase development (if faster, denser DIMMs were not available then) and that code has survived, unchanged, to this day.

The Mac Pro has a reputation for being able to mix sizes and speeds, and leave slots open, and still adjust to the lowest common settings. It may be that it goes even farther and shifts down a speed to accommodate the performance of the installed DIMMs as well.

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Answer 6

macnmotion Author

Level 1

4 points

Feb 13, 2018 7:40 AM in response to Grant Bennet-Alder

Thanks again. Yes it turns out that the faster RAM was not available at the time this machine was purchased, this was the best the owner could get. He had it shipped from USA, nothing was available in Thailand at that time.

The machine running 64GB has been stable with zero reported errors for about 2 days now, so I'm going to leave it as is. I do some heavy lifting with this machine, processing astrophotography, which uses everything I'm able to throw at it. While I'd like to be able to use all 128GB I'll settle for 64.

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Answer 7

Feb 13, 2018 8:22 AM in response to macnmotion

Regarding the DIMMs with ECC errors:

That Vendor, OWC is the US, provides a lifetime exchange warranty. If you can wait (many weeks) for surface shipping, they should exchange the ones that are no longer working for new ones of the same size and type, for free.

If you can provide a credit card number, they may be willing to advance ship today, and wait for your old ones to return. (they only charge your card if the old ones do not arrive.)

The OWC sticker is the only "proof of purchase" required.

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Answer 8

macnmotion Author

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4 points

Feb 12, 2018 7:12 PM in response to Grant Bennet-Alder

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Answer 9

Feb 12, 2018 7:17 AM in response to macnmotion

User Tip: Mac Pro and Error Correcting Code RAM Memory

.

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Answer 10

Feb 12, 2018 6:55 PM in response to Grant Bennet-Alder

The page you showed is indicating you are using the wrong memory modules for your Mac Pro. It takes 1866MHz DIMMS, and most Macs do not gearshift happily and use different speed DIMMS.

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ECC errors and fan speed issue Mac Pro (late 2013)

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